method updateValue

Source

void updateValue(Object update, {bool force: false}) {
  _valueReady = true;
  if (update is ValueUpdate) {
    _lastValueUpdate = update;
    callbacks.forEach((callback, qos) {
      callback(_lastValueUpdate);
    });
  } else if (_lastValueUpdate == null ||
      _lastValueUpdate.value != update ||
      force) {
    _lastValueUpdate = new ValueUpdate(update);
    callbacks.forEach((callback, qos) {
      callback(_lastValueUpdate);
    });
  }
}